Umkomasia (megasporophyll): part 1 of a reassessment of Gondwana Triassic plant genera and a reclassification of some previously attributed

Abstract

Anderson, H.M., Barbacka, M.K., Bamford, M., Holmes, W.B.K. & Anderson, J.M., 8 February 2019. Umkomasia (megasporophyll): Part 1 of a reassessment of Gondwana Triassic plant genera and a reclassification of some previously attributed. Alcheringa 43, 43–70. ISSN 0311-5518.The genus Umkomasia, a megasporophyll, belonging to the pteridosperms (seed ferns) in the family Umkomasiaceae (Corystospermaceae), is reassessed comprehensively worldwide. All previous records are analysed. Certain fertile structures previously attributed are reclassified. Umkomasia is shown to be restricted to the Triassic of Gondwana where it is associated with the genus Pteruchus, a microsporophyll, and the genus Dicroidium, a vegetative leaf. It is well represented from Argentina, Australia and southern Africa where the Molteno Formation is by far the most comprehensively sampled with eight species described. Two specimens from the upper Permian of India attributed to Umkomasia are reclassified as cf. Arberiopsis sp. A whorled fertile structure from Antarctica, previously assigned to Umkomasia, is reclassified in a new genus as Axsmithia uniramia. Another compression fossil and the permineralized Umkomasia resinosa remain as valid records from Antarctica. The material described as Umkomasia from the Triassic of China is reclassified as Stenorachis asiatica. The Lower Jurassic record from Germany is placed in a new genus as Kirchmuellia franconica. The records of Umkomasia sp. from the Rhaetic of Germany are reclassified as cf. Kirchmuellia sp. and the single specimen from the Jurassic of Libya as genus et sp. indet. The Lower Cretaceous record from Mongolia has been reclassified by other researchers as Doylea mongolica. A pictorial key to Umkomasia species is provided, geographic and stratigraphic distributions are tabulated.Heidi M. Anderson, [hmsholmes@googlemail.com], Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 20150, South Africa; Maria Barbacka [maria.barbacka@gmail.com] W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, Kraków 31-512, Poland, Botanical Department, Hungarian Natural History Museumartmem H-1431, Budapest, Pf. 137, Hungary; Marion K. Bamford [marion.bamford@wits.ac.za] Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 20150, South Africa; W. B. Keith Holmes [wbkholmes@hotmail.com] 46 Kurrajong Street, Dorrigo, NSW 2453, Australia, University of New England, Armidale, NSW 2351, Australia; John M. Anderson [jmanderson.gondwana@googlemail.com] Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 20150, South Africa.